The hand-operated motorized lawn mowers currently available for gardening have a self-supporting chassis which, as the central element, absorbs all the operating forces and on which all the add-on parts are fastened. The manufacturer supplies these lawn mowers in a small number of predetermined variations, which differ essentially only in respect of their cutting width and their drive. The individual mass-produced types of mower are adapted more or less to the requirements and the wishes of the consumers and are equipped either with an internal combustion engine or with an electric motor with mains connection or storage-battery operation, it obviously being necessary for the power of the motors to be adapted to the cutting width. Once the customer has bought a lawn mower of a certain type, it is no longer possible to make any changes, in particular in respect of power and cutting width. If the customer was mistaken in respect of the set-up which is optimal for his/her requirements, or there was a change in requirements on account of a newly acquired surface area requiring cutting, this change could only be taken into account by a new type of mower, accordingly better adapted to the requirements, being bought. Even with damage to a part, for example the chassis, or with failure of a functional element, repair of the conventional mass-produced lawn mowers was not economically viable, with the result that, in this case too, it was necessary to make a new purchase.
On the other hand, the types of lawn mower brought out in a small number of predetermined series allowed rational semi-automatic production, which had a favorable effect on the price for the consumer.
In contrast to the abovemetioned lawn movers, in which there is provided a rigid chassis which accommodates the running wheels and bears the add-on parts fastened rigidly on it, U.S. Pat. No. 3,537,720 has disclosed a lawn mower in which two wheel-support frames are mounted such that they can be moved to a limited extent with one another and with the add-on parts. In this case, two lateral frame parts which accommodate the running wheels are connected to a transversely running rear wall via articulation elements, and the cutting-unit hood, which bears the motor, is connected to the lateral frame parts via two further articulation elements. This is intended to achieve the situation where, in the case of uneven terrain, all the wheels remain in contact with the ground. As a result, it is intended for the gap between the mower and the ground to be kept small in order to prevent stones or the like which are slug out by the cutting blades from escaping in the outward direction and causing injuries. This risk of hard objects being slug out is intended to be prevented by a trailing roller rolling on the ground, as a result of which the gap, which is open to the rear, is covered in its entirety. In this specific construction, this known mower is obviously mass-produced. Modifications are not provided.
A lawn mower designed in modular fashion in accordance with the generic type is known from EP-A-0 193 186. This lawn mower has, as its main module, a core part onto which it is possible to add, in the direction of travel of the lawn mower, front and rear additional housing parts which bear the running wheels. This is intended to make it possible for one and the same additional part containing, for example, the wheels and the handle to be combined with different core parts, for example with larger and/or wider core parts.
U.S. Pat. No. 2,265,545 discloses a lawn mower with a rigid frame with a motor bearing and axle bearings and an articulated guide bar and with a running gear, a motor unit and a cutting unit. For the purpose of space-saving dispatch from the factory to the customer or store owner, these various parts are intended to be packaged separately from one another and to be assembled only at the intended destination. Different possible combinations are not provided here.
A lawn mower which may optionally be equipped with different additional parts, e.g. with rigid or articulated handles or either adjustable or fixed wheels, is known from U.S. Pat. No. 4,422,283.
the object of the invention is to provide a modular-construction hand-operated motorized lawn mower which, in conjunction with a limited number of differently designed and/or dimensioned main and additional modules, makes it possible for a wide range of individually adapted types of lawn mower to be constructed and made available at a reasonable price.
The set object is achieved by the features specified in the defining part of patent claim 1.
It is possible in the same way to construct, in modular fashion, a hand-operated motorized verticutting implement according to patent claim 2, a hand-operated motorized sweeping device according to patent claim 3 or a hand-operated motorized device for loosening the soil or for taking in and blowing out leaves according to patent claim 4.
Since the rigid frame may be designed in a comparatively straightforward manner such that, without any damage being caused, it absorbs all the loading occurring in unusual operating states, optimum adaptation to lawn mowers of different sizes and/or powers.
Despite the variety of different types of lawn mower which are to be produced in a customer-specific manner, cost-effective production can take place in a manner known per se in that, with computer aid, on a production line, the respectively necessary modules are fed and fitted, if appropriate, automatically.
Further configurations of the invention can be gathered from the subclaims. A suitable running gear, in general, is a double-axle running gear with four wheels which are arranged in a manner known per se such that they can be height-adjusted together, via an adjusting lever, in order for it to be possible for the operating height to be adjusted. Instead of the rear wheels, it is also possible for a running roller to be arranged in a module of corresponding design. The invention also makes it possible, instead of the cutting unit for lawn-mowing purposes, to arrange other tool subassemblies, for example verticutting blades or a device for loosening the soil or else a device for sweeping together or for taking in and blowing out, for example, leaves.